Information Notice 1986-99, Degradation of Steel Containment

Degradation of Steel Containment

ML031250248
Person / Time
Site:	Beaver Valley, Millstone, Hatch, Monticello, Calvert Cliffs, Dresden, Davis Besse, Peach Bottom, Browns Ferry, Salem, Oconee, Mcguire, Nine Mile Point, Palisades, Palo Verde, Perry, Indian Point, Fermi, Kewaunee, Catawba, Harris, Wolf Creek, Saint Lucie, Point Beach, Oyster Creek, Watts Bar, Hope Creek, Grand Gulf, Cooper, Sequoyah, Byron, Pilgrim, Arkansas Nuclear, Braidwood, Susquehanna, Summer, Prairie Island, Columbia, Seabrook, Brunswick, Surry, Limerick, North Anna, Turkey Point, River Bend, Vermont Yankee, Crystal River, Haddam Neck, Ginna, Diablo Canyon, Callaway, Vogtle, Waterford, Duane Arnold, Farley, Robinson, Clinton, South Texas, San Onofre, Cook, Comanche Peak, Yankee Rowe, Maine Yankee, Quad Cities, Humboldt Bay, La Crosse, Big Rock Point, Rancho Seco, Zion, Midland, Bellefonte, Fort Calhoun, FitzPatrick, McGuire, LaSalle, 05000000, Zimmer, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant, Skagit, Marble Hill, Crane
Issue date:	12/08/1986
From:	Jordan E L NRC/IE
To:
References
IN-86-099, NUDOCS 8612050463
Download: ML031250248 (4)

SSINS No.: 6835IN 86-99UNITED STATESNUCLEAR REGULATORY COMMISSIONOFFICE OF INSPECTION AND ENFORCEMENTWASHINGTON, D.C. 20555December 8, 1986IE INFORMATION NOTICE NO. 86-99: DEGRADATION OF STEEL CONTAINMENTS

Addressees

All nuclear power reactor facilities holding an operating license or a con-struction permit.

Purpose

This notice is to provide recipients with current information of a potentiallysignificant safety problem regarding the degradation of a steel containmentresulting from corrosion. It is expected that recipients will review thisinformation for applicability to their facilities and consider actions, asappropriate, to promptly recognize or prevent a similar problem from occurring.However, suggestions contained in this notice do not constitute NRC requirements;therefore, no specific action or written response is required.

Description of Circumstances

The Oyster Creek Nuclear Generating Station first discovered water in the gapbetween the boiling-water-reactor drywell and the concrete shield in 1980 andbegan investigation of the cause in 1983. It appeared that the collection ofwater varied from a few drops to 2 gallons per minute, depending on whetherthe unit was in operation or an outage for refueling. During the spring andsummer of 1986, the licensee planned work to identify and eliminate this waterproblem. The bellows at the drywell to cavity seal was repaired and a gasketwas replaced, thus stopping the leakage. Since the bellows is located at thetop of the drywell and the region above the bellows is flooded during refueling,it would explain why leakage was high during refueling and low during operation.To determine if the water in the gap had caused damaged to the steel contain-ment, the licensee measured the wall thickness, using an ultrasonic testing (UT)technique at two elevations. The 51-ft level near the drywell seal was sound,but there appeared to be loss of metal on the gap side at the 11-ft 3-in. levelimmediately above the concrete floor. In this area, the gap is packed withsand and contains five equally spaced drain pipes (see attached Figure 1). Atotal of 143 measurements were made at this level and 60 indicated a reductionin thickness of more than 1/4 in. from the drawing thickness of 1.154 in.These readings were found throughout seven of the ten downcomer bays. Thelicensee plans to cut the steel containment and remove about 12 samples toconfirm and evaluate the corrosion damage.8612050463 IN 86-99December 8, 1986 The licensee plans to remove a section of the drain pipe to perform a visualexamination of the outside of the drywell. Wipe samples will be taken fromseveral areas and a chemical analysis will be performed. Sand samples willbe taken adjacent to the core holes and will be analyzed for chemicals, bac-teria, and water composition. Some channels are being cut in the concretefloor that is inside the drywell to provide access for further UT examinationof the containment-sand interface.Discussion:The purpose of the sand is to act as a cushion and allow expansion of thedrywell during operation. The steel containment is in contact with sand inthose areas where corrosion has been detected. The containment material isASTM A-212 Grade B carbon steel plate. The licensee stated that the outsidesurface was protected with a red lead coating from above the drywell down toabout the 10-ft. level, which means that the interface between the lead paintand the unprotected steel was in contact with wet sand. Red lead protectssteel by providing a stable and impenetrable surface, but the steel is sacri-ficial with respect to the lead in dilute, acidic water conditions.It is possible that condensation during initial construction, moisture pickupthrough the drain line during operation, and the leaking bellows wetted thesand, thereby causing corrosion of the containment steel plates. During con-struction, water was seen running down the outside of containment into thesand. The five drain lines, as well as other penetrations in the concreteshield, are open during operation and would allow moist air to enter and riseup the gap and later cool and condense as water. Water also was able to enterthe gap through the holes in the bellows during refueling until repairs weremade.A related matter is discussed in IE Information Notice 86-35, "Fire in Com-pressible Material at Dresden Unit 3," where a large amount of water was usedto extinguish the slowly burning fire between the drywell and the concreteshield. Oyster Creek uses different filler material.The NRC is continuing to obtain and evaluate pertinent information. If spe-cific actions are required, an additional notification will be made.No specific action or written response is required by this informationnotice. If you have any questions about this matter, please contact theRegional Administrator of the appropriate regional office or this office.1dwardLJordan, DirectorDivision f Emergency Preparednessand Engineering ResponseOffice of Inspection and Enforcement

Technical Contact:

Paul Cortland, IE(301) 492-4175

Attachments:

1. Figure 1, Sketch of Possible Degraded Area2. List of Recently Issued IE Information Notices yAttachment 1IN 86-99December 8, 1986 Sketch of Possible Degraded Areas3 IN. ANNULAR SPACEWITH FILLER MATFRtI&pRYWELL1.154 IN. DESIGNTHICKNESSELEVATION 11 FT.ELEVATION 10 FT. 3*CONCRETE. * *OFLOORele4 4 *CONCRETEoo

• 8 Oo* uau°uo0*~ U,^ D ° /4 DRAINAGE CHANNEL 4 4 /A WITH 4 IN. DIA. 00.S SAND FILLED DRAINkh oa PIPE (EVERY OTHERW A <DRYWELL VENT) & 4A U(/ -v,a q0 .,04Figure 1 Attachment 2IN 86-99December 8. 1986LIST OF RECENTLY ISSUEDIE INFORMATION NOTICESInformation -Date ofNotice No. Subject Issue Issued to86-21 Recognition Of American 12/4/86 All power reactorSup. 1 Society Of Mechanical facilities holdingEngineers Accreditation an O or CPProgram For N Stamp Holders86-98 Offsite Medical Services 12/2/86 All power reactorfacilities holdingan OL or CP86-97 Emergency Comaunications 11/28/86 All power reactorSystem facilities holdingan OL or CP and fuelfacilities86-96 Heat Exchanger Fouling Can 11/20/86 All power reactorCause Inadequate Operability facilities holdingOf Service Water Systems an OL or CP86-95 Leak Testing Iodine125 11/14/86 All NRC licenseesSealed Sources In ilx, Inc. authorized to useImaging Devices and Bone Lia1 Inc. imagingMiners Analyzers devices86-94 Hilti Contrete Expansion 11/6/86 All power reactorAnchor Bolts facilities holdingan OL or CP86-93 IE3 85-03 Evaluation Of 11/3/86 All power reactorMotor-Operators Identifies facilities holdingImproper Torque Switch an OL or CPSettings86-82 Failures Of Scram Discharge 11/4/86 All power reactorRev. 1 Volume Vent And Drain Valves facilities holdingan OL or CP86-92 Pressurizer Safety Valve 11/4/86 All PiR facilitiesReliability holding an OL or CPOL

• operating LicenseCP

• Construction Permit, ....UNITED STATESNUCLEAR REGULATORY COMMISSIONWASHINGTON, D.C. 2055OFFICIAL BUSINESSPENALTY FOR PRIVATE USE. S300FIRST CLASS ALtP0STA1N 6 FEES PAIDUSNACWASI. D.C.PERMI No. 04713357510360n 1 IC01CYlFB11AlNUS CORPLFSLYLE NGABERLICENSING ENGINEER2536 COUNTRYSIOE BLVOCLEARWATER FL 33575